Turbocharged and supercharged engines may be configured to compress ambient air entering the engine in order to increase power. Because compression of the air may cause an increase in air temperature, a charge air cooler may be utilized to cool the heated air thereby increasing its density and further increasing the potential power of the engine. If the humidity of the ambient air is high, however, condensation (e.g., water droplets) may form on internal surfaces of the charge air cooler that are cooler than the dew point of the compressed air. During transient conditions such as hard vehicle acceleration, these water droplets may be blown out of the charge air cooler and into the combustion chambers of the engine resulting in increased potential for engine misfire, loss of torque and engine speed, and incomplete combustion, for example.
The inventors have recognized the above issues and offer an approach to at least partly address them. In one embodiment, an engine method comprises increasing intake air flow velocity through a charge air cooler and coordinately adjusting a position of one or more of an intake manifold throttle and a turbocharger wastegate in response to the increased intake air flow velocity to maintain torque.
In this way, during conditions where condensation is likely to form, intake air flow velocity through the charge air cooler may be increased to break surface tension and prevent the formation of condensation within the charge air cooler. The torque disturbances that may result from the increased intake air velocity may be compensated for by adjusting the throttle and wastegate, maintaining requested torque.
In one example, the charge air cooler may include a valve configured to open during low-condensation conditions (e.g., high intake air flow velocity), allowing the intake air to flow through the entire volume of the charge air cooler. The valve may be configured to close during high-condensation conditions (e.g., low intake air flow velocity), blocking the intake air from flowing through the entire charge air cooler and instead directing the intake air through a portion of the charge air cooler. By routing the intake air through only a portion of the volume of the charge air cooler instead of the entire volume, intake air flow velocity increases and the formation of condensation within the charge air cooler decreases. Further, the throttle and wastegate may be coordinately adjusted with the charge air cooler valve to provide requested torque.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.